(1) Field of Invention
The present invention relates to roofing shingles and, more particularly, to a lightweight insulated stone roofing shingle assembly.
(2) Description of Related Art
The use of natural slate, stone, clay, ceramic, or terracotta as a roofing medium goes back several centuries. These materials by their nature are relatively heavy when compared to other roofing materials such as wood and asphalt. The excessive weight of such shingles limits use of these materials to structures specifically designed to support heavier roof loads. Although a variety of stone and other materials have been used as roofing shingles, slate and similar stones are long known as the leading material varieties available. It should be noted that for convenience purposes, the term “slate” is being used herein to refer to any type of roofing material, such as stone, porcelain, clay, ceramic, terracotta, etc. Slate is a unique geological material possessing certain inherent strengths and weathering characteristics enabling it to withstand severe environmental elements for many decades and, in some cases, centuries. A good roofing slate will have a low water absorption rate, high weathering resistance from exposure to sun and chemical attack from rain, be unaffected by freeze thaw cycles, and possess an ability to not easily break when subject to flexural loads.
Installation labor costs are widely known to be higher for slate roofs than for other roofing products due to three key factors, including: (1) weight of material, (2) method of installation, and (3) handling breakage. Slate roofing materials can weigh several times that of other roofing materials, such as composite or asphalt shingles. The added weight of slate roofing materials means that there is more weight to lift, move, handle, and install, all of which add cost and risk. Further, roofing slates are typically drilled or punched with two holes for installation. Installed slates hang on two nails that have been hammered into the roofing substrate by the installer. The process of vertically holding a slate in place while positioning nails, then nailing carefully so as to not hit the slate is difficult. The nailing process results in 1%-2% loss due to damage from inadvertent hammer blows. Additionally, automatic fastening guns cannot be used on slate shingles due to damage from impact forces, further slowing install time.
Thus, a continuing need exists for a lightweight shingle assembly that is easier to install than traditional slate shingles and less prone to breakage during installation and handling.